petitioner petitioner /pəˈtɪʃənɝ/

noun

1. () One praying humbly for something  ( requester , suppliant , supplicant , petitioner )
   one praying humbly for something
    A suppliant for her favors
   a suppliant for her favors
   
   
2. Someone who petitions a court for redress of a grievance or recovery of a right  ( petitioner , suer )
   someone who petitions a court for redress of a grievance or recovery of a right